The immunohistochemical staining method is to clarify the local existence (localized position) of a substance, which exists inside a tissue cell and has antigenicity, by utilizing a specific immune reaction called an antigen-antibody reaction.
Operations for the immunohistochemical staining are generally performed through a plurality of steps as follows. A first step is a deparaffinization step of dissolving paraffin embedding a specimen, which has been attached onto a slide glass and immobilized using a formalin solution, etc., with an organic solvent. A second step is a hydrophilization step of removing the organic solvent to increase affinity of the specimen to water. A third step is an antigen retrieval step of performing treatment to increase immuno-reactivity. A fourth step is a primary antibody applying step of applying an antibody that reacts with the antigen in the specimen. A fifth step is a detection step of applying a reagent to detect the antibody having reacted. A sixth step is a color developing step of applying a reagent to visualize the detection reagent. A seventh step is a staining of nuclei with a different color to confirm the morphology feature of tissues easily.
Various apparatuses for carrying out general staining processes, including the above-described immunohistochemical staining process, have been proposed so far. In those apparatuses, a cover placed on a slide glass serves to fill or hold a reagent, etc. For example, Patent Document 1 discloses a cover for a base comprising a main body that is positioned above a base, and that defines a cavity to form a reaction chamber, and a projected portion that projects from the main body, and that defines a fluid container in fluid communication with the cavity when the cover is mounted to the base.
Patent Document 2 discloses an apparatus for treating a human or animal cell sample with a treatment liquid, the apparatus comprising means for applying the treatment liquid to a surface of a slide on which the sample is held, and means for determining a contour of the sample with setting a cover tile, which has a recessed surface, on a slide, wherein the apparatus further comprises means for applying a sealing liquid to a joined boundary between the slide and the cover tile from the outside of a cavity, thereby sealing off a gap generated between the cover tile and the slide.
Patent Document 3 discloses an apparatus for extracting biological molecules from a tissue specimen, the apparatus comprising a base having an upper surface and a bottom surface, the base holding the tissue specimen on the upper surface of the base, a slide cover placed on the upper surface of the base and having an inner surface, the upper surface of the base and the inner surface of the slide cover forming a space to hold an extraction buffer solution, and a temperature controller connected to the bottom surface of the base. Patent Document 3 further discloses the following features. The inner surface of the slide cover projects toward the base in a central portion the slide cover, whereby the space formed by the upper surface of the base and the inner surface of the slide cover is shallowed around a central portion (Claim 3). The slide cover has an opening formed in the central portion to allow the extraction buffer solution to be added into the space between the upper surface of the base and the inner surface of the slide cover (Claim 15). The slide cover further includes at least one outer surface hole in a peripheral portion thereof (Claim 16).